Making with Metal

3D Metal Printing

Agustin Cruz

Issue 57, April 2022

Tired of printing plastic? We're told this is the first open-source 3D Metal Printer using an electron beam!

Agustin recently got in touch with us about his 3D Metal printer project, which he has been developing for the last several years. With the aim to make 3D metal printing affordable to the general public, Agustin is now crowdfunding the project to get more support. Not purely for financial support but, more importantly, to get more brain power to make it a success.

We caught up with Agustin to find out more.

Welcome to DIYODE Mag, Agustin. Please introduce yourself to our readers.

I'm an electrical engineer in Chile, with more than 10 years of experience building laser machines, CNC machines, robots, laboratory equipment among other things.

My project consists of an Open-source, low-cost 3D Metal Printer for developing and low income countries, using an electron beam to sinter the metal powder.

Your 3D metal printer is very impressive. What was the motivation for building it?

The goal is to make 3D Metal Printing more affordable to the general public, hospitals, small institutions, organizations and companies around the world. Specifically for developing and low income countries. This project fills a gap that no open hardware successfully fills.

3D Metal Printing is an impactful tool. Making it more accessible will democratize science, engineering and empower people. This low-cost hardware will be able to accelerate innovations in and lower barriers to scientific research.

Brilliant! We admire makers, like yourself, trying to provide real-world open-source solutions to the community. What metals does your printer support, and can you give us a broad overview of how it works?

The technical goal is to make it capable of working with titanium, stainless steel, aluminum, and other 3D metal printing powders.

It uses an electron beam with a focus point diameter of around 0.1mm, and the thickness of each layer of metal powder is 0.05mm to 0.1mm.

This 3D Metal Printer will use already available open source 3D Printing software, like Cura, Slic3r and others. So there is no proprietary software and no black boxes.

The initial work is taking place in Chile, however, I have started to build and sustain collaboration with people around the world through collaborative websites, social networks, YouTube and other channels.

Can you tell us about the working principles of 3D metal printing?

This printer uses an electron beam to selectively melt each layer of metal powder, causing the powder particles to fuse together. After one layer is complete, the build platform is moved down one layer in height. The re-coater comes in again with a fresh layer of powder, and the electron beam starts to induce the fusion of powder particles, causing the new layer to form. This process is repeated until the entire part is finished, making a solid metal part. Each layer height is around 0.05mm to 0.1mm thickness.

The diagram shown here better explains the working principle of the 3D Metal Printer. The electron beam travels through a set of magnetic lenses that focus the beam onto the working area for sintering the metal powder.

There are two types of magnetic lenses:

Focus lenses: focus the electron beam to a small point (less than 0.5mm diameter).

Deflection lenses: moves the focused beam in the X-Y plane according to the 2D design of each layer (2D slices of a 3D object).

Both types of lenses are made of coils and controlled by Arduino boards, in this case.

How does your method compare to laser sintering?

When you print a 3D Metal part with a laser it is very important to take into account heat deformation and cracks when the piece cools itself. If you need a durable and strong part, you will also need a powerful oven to heat the metal part and slowly cool it to eliminate internal stress.

With electron beam printing you don't need an additional oven. The electron beam can be defocused to pre-heat the powder, so you focus again to start the sintering process according to your design.

What are the advantages of using an electron beam for sintering the metal powder?

The advantages of using an electron beam for 3D metal printing are:

  • Higher density and strength due to a full melt of the powder
  • Faster printing process
  • Non-sintered powder can be recycled
  • Fewer supports required compared to laser powder bed fusion

What is your current prototype able to achieve and what’s needed to start printing 3D prints?

At this moment the prototype is capable of generating a 0.5mm diameter electron beam, focusing it on a metal surface and moving it in X-Y axis using the focus and deflection coils (as you can see in the above mentioned diagram). In this way, it is possible to move a fine spot, heat and weld a metal piece using the electron beam.

At this moment, I'm working on the electron gun to reduce the size of the focused spot from 0.5mm to 0.1mm in diameter or less.

After that technical milestone is met, the next step will be to add the Z-axis and a metal powder re-coater. The Z-axis will be composed of a stepper motor, guides, linear bearings and a controller.

Tell us about any safety aspects.

This project is for people with experience with high voltage. The electron gun used in this project is very similar to the electron gun used in old televisions. It works with high voltage (10-20kv) and uses thick steel walls the same way old television used leaded glass to block any radiation.

We imagine you have invested a lot of time and money into this?

Currently there is an advanced functional prototype, with more than 5 years of research and development with its own capital. This prototype is used to carry out initial tests and verify technical aspects before making larger investments.

The most important technical challenges are already 70% solved. The functional prototype is composed of a vacuum chamber made of stainless steel, a vacuum pump system, an electron gun, high voltage power sources, electrical connections, cooling systems, sensors, among others.

At this time the prototype is capable of generating a 0.5mm diameter electron beam, focusing it on a metal surface and moving it in XY axis. In this way, it is possible to heat a metal piece using the electron beam. Currently, optimization of the electron gun is being worked on, evaluating different configurations to reduce the size of the spot from 0.5mm to 0.1mm in diameter or less.

After that technical milestone is met, the next step will be to add the Z-axis and a metal powder re-coater. The Z axis will be composed of a stepper motor, guides, linear bearings and a controller.

The metal powder will be ordered and 3D printing tests will be carried out on different metals (titanium, stainless steel, aluminium, etc.)

You can see the video of the 3D Metal Printer Electron gun tests here:

Focus and deflection drivers, using I2C Digital to Analog converters and Darlington amplifiers. All boards are controlled by Arduino microcontrollers.

Tell us more about the electronics circuitry and coding

The electronics are based on Arduino boards to make it easier to modify and distribute by anyone. All the code, design and schematics will be shared online.

In this picture I'm testing the focus and deflection coil controllers, to focus and move the electron beam in the X-Y plane. These boards make it possible to drive the coils using Arduino boards. Each board drives a single coil.

Arduino has little power output, and its Digital-to-Analog converter is not suitable to drive a coil directly. So, these boards take I2C digital instructions from Arduino, convert them to an analog voltage and then amplify it with Darlington transistors in a totem-pole configuration.

These are linear amplifiers (not switching ON/OFF), so BJT and Darlington transistors are better choice than MOSFETs.

What essential milestones will you generate and the next steps?

The first essential milestone is the focusing of the electron gun to a 0.1mm diameter spot. The current electron gun is capable of focusing to a 0.5mm diameter spot. This will offer the possibility to 3D metal printing very fine details.

Then, the next step is integrating the Z axis, the powder coating system, and make operational 3D Metal Printing tests.

Tell us what made you post this on Patreon. What is your goal?

This is what I do fulltime. And it's not cheap. Doing all this takes a lot of time and effort.

Now the project is opening to the community inside a crowdfunding model. The design, tests, updates, will be shared so I can receive some support and continue working 100% in this project

You can support the 3D Metal Printer Project here:

We notice you have results, methods, schematics and design files available for people who support you. Does this mean makers can attempt to make one for themselves or is this to get them to participate in your build?

This project will stress the opportunities that are presented in pre-production, co-creation, customization, and collaboration through open processes of the 3D Metal Printer development. The final 3D Metal Printer can be created, modified, used, or distributed by anyone.

Specifically, the collaboration will be managed in two branches:

  • Software collaboration: The 3D Metal Printer project will create a GitHub page, so anyone can browse and download software repositories but only registered users can contribute content to repositories. With a registered user account, users can have discussions, manage repositories, submit software contributions to others’ repositories, and review code changes.
  • Hardware collaboration: The project will create a parent category for open science hardware project in GOSH Open Hardware website, where Hardware and operational tests will be fully documented, so anyone can browse and download the schematics, designs, etc. Only registered users can have discussions and submit hardware contributions to others.

Who will benefit from this 3D Metal Printer project?

Our aim was always to connect a global network of individuals and groups from diverse cultures, low resource environments, as they also exist in Chile, America, Europe, as well as everywhere on the globe.

The targets are professionals and amateurs, particularly in low incomes countries. Participation is not restricted to any particular background, country, race, sex, religion, etc. The use of 3D printing in a healthcare system for rural developing communities allows for a unique insight into product and technology adoption processes in developing communities.

For hospitals located away from major cities, 3D Metal Printing will be practical when supplies run low. This is especially important in farming communities where patients from the nearby fields who come in with work-related injuries could be outfitted with custom splints that are 3D Metal Printed as needed.

We find that entrepreneurs will benefit from this project. Especially early stage entrepreneurs that are not yet financially secure enough to easily afford a 3D Metal Printer. Increasing access for these entrepreneurs ensures greater representation and impact, paving pathways to get these deep-tech innovations more efficiently into the market. Adopting open-source approaches play a key role in this process. The 3D Metal Printer design, plans, videos, schematics will be open and free for any person in the world.

Is there anything else we haven't covered that our readers should know about?

The 3D Metal Printer Project will have a website wiki with the full documentation of the step-by-step instructions to build the 3D Metal Printer, hardware designs, the source code, videos, project reports, etc. Meanwhile the official communication way is the Patreon page.

Also, this material will be permanently available in collaborative websites like GitHub, GOSH Open Hardware website, social networks, YouTube and other channels.

All these materials will be released under OSHWA-compatible licenses for hardware, free software licenses for software, and CC BY 4.0 or CC BY-SA 4.0 for others.

We invite freelancers, creatives, hackers and artists, alongside researchers from established research institutions and professional hardware/software developers.

We wish you all the best with it, Agustin. Let us know how you get on.

3D Metal Printer building process: assembly of parts before welding
3D Metal Printer building process: main body already TIG welded. All parts were made from stainless steel
Difussion Pump oil trap, for preventing oil contamination. Stainless steel parts were laser cut and TIG welded
Focus and deflection coils assembly.
Another view for the focus and deflection coil assembly
All parts were designed in 2D modelling software and laser cut in stainless steel.
Electron gun development in stainless steel.
Making the PCB boards at home.
Focus and Deflexion System